The invention relates to a method for the sealing of an electrical component, particularly a relay, comprising a housing exhibiting individual apertures or joints. First a fleece, i.e. a tissue or non woven fabric covering having a high capillary absorption capacity, is placed over the housing apertures to be sealed. This fleece is subsequently impregnated with a low-viscosity, age-hardenable casting resin.
A method of this type is known from U.S. Pat. No. 4,176,241. It is essentially employed for the purpose of sealing the housing apertures for connecting pins and the housing joints between a base and a protective cap. With the use of fleece, it is possible to effectively distribute a small quantity of casting resin over the entire surface and, in particular, to convey it to the housing aperatures without thus contaminating the projecting connecting pins and without significantly increasing the overall height of a relay or of a similar component.
For the sealing operation it is decisive that the fleece lie in a planar fashion on the housing surface to be sealed, particularly also at the edges, since otherwise unsealed locations can occur. In order to accomplish this, it has already been proposed that during the introduction of the casting resin, a frame be placed on the fleece so as to weight the fleece at the edges until the age-hardening of the casting resin occurs. However, this represents an increased fabrication expense since these frames must consist of a special material, for example polytetrafluoroethylene, in order to avoid an adhesion of the casting resin on the frame. On account of the comparatively long duration of the age-hardening operation (several hours), a large number of these costly frames must be available; moreover, the latter must be cleansed after each use in order to be able to be further used.